Multiple stage shale eduction process



April 5, 1949. P. H. JONES 2,466,593

MULTIPLE STAGE SHALE EDUCTION PROCESS Filed Jan. 17, 1944 ts-Sheet 2 Absar er jz u INVHVTOR.

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Patented Apr. 5,1949

UNITED STATES PATENT oFFIcE MULTIPLE STAGE SHALE EDI JCTION PROCESS Philip H. Jones, Redondo Beach, Calif., assignor to Union Oil Company of California, Los Angeles, Calit, a corporation of California Application January 17, 1944, Serial No- 518,570

Claims. 1

solid oil-bearing or producing materials, particularly to recover shale oil from-oil shales. The recovery of the oil from the oil-bearing or producing material may be accomplished by roasting in a kiln the oil-bearing or producing material at high temperatures sufilcien-t toeduct the oil and separate it from the mineral matter. These processes have not been entirely satisfactory because the shale gas produced in the above mentioned processes usually contact flue gases and thereby become contaminated by same, with a resulting loss of valuable hydrocarbon liquid and gases. In such processes the educted oil is subject to a long period of exposure to high temperatures. As a result of this relatively long time of contact an undesirably large amount of the hydrocarbonis converted to non-condensable gases and carbon or carbonaceous solids. There are still other processes which educt shale oil from oil shale by means of external heat alone, in a suitable apparatus, or by external heat in conjunction with a limited amount of steam.

The above mentioned methods have proved themselves of somewhat limited value in many respects because the oil educted is usually of low specific gravity, containing a reduced percentage of lubricating stock and waxes and apexcessive amount of unsaturates. Another disadvantage in the above mentioned processes is the excessive production of undesirable constituents, such as carbon monoxide and hydrocarbon gases. 1 have discovered a process by which oil and hydrocarbon vapors may be readily and efficiently recovered at relatively low temperatures from oilbearing solid substances by means of the :ensible heat of hot flue gas and hot lean shale gas in conjunction with superheated steam, in a semicontinuous operation with a resulting uniform treatment. My process overcomes the above mentioned dificulties present in said processes employed for the eduction and recovery of oils from shales and the like, and permits a maximum recovery of the oils with a minimum amount of 2 The above cycle consists of the following nine stages: First, a purging stage, wherein air is removed from the shale packed retort by means of hot flue gases; second. a partial eductlon stage, wherein the said shale is partially educted by means of relatively hot rich shale gas and steam; third, a complete eduction stage, wherein the partially educted shale is completely educted by means of hot lean shale gas and steam; fourth,

a second firing stage, wherein the completely educted shale is heated to greater temperatures by means of hot flue gases; fifth, a first firing stage, wherein the carbonaceous material on the hot educted shale is burned off by means of fuel gas and air; sixth, a second preheating stage, wherein the hot educted shale by means of heat exchange gives up heat to hot lean shale gas and steam introduced .therein; seventh, a first preheating stage, wherein the somewhat cool spent shale by means of heat exchange gives up heat to cool lean shale gas and steam introduced therein; eighth, a discharging stage, wherein the cold spent shale is removed from the retort; ninth, a

refill stage, wherein fresh crushed shale is introduced into said retort.

It is to be understood that the above mentioned series may consist of any number of retorts arranged in any desirable manner, but the preferred series should consists of nine in number. In order to further clarify my invention each of the nine retorts will be operating in a different stage of the above mentioned cycle at any designated time during the operation of the process.

In the drawings, an apparatus adapted to perform the method according to the invention is shown in a merely diagrammatic way. Figure 1 shows the nine stages of a complete cycle wherein retorts A, B, C, D, E, F, G, and I, represent the respective stages through which retort A passes during the process of the invention. Figure 2 shows the entire apparatus and necessary manifold by which each and every retort can be transfer-red from one stage to the next in the above cracking, and avoids the commingling of the shale designated intervals. 2

Referring to Figure 1, rich crushed shale in purging retort A is heated and purged of air by means of moderately hot flue gas from second firing retort D by means of line i. The air and fiue gas in purging retort A is removed by means of lines 2 and 3 and disposed of as desired. After purging, valves are changed to put purging retort A into the second stage of eduction, as shown by second eduction retort B. Relatively hot rich shale gas and steam are introduced into second eduction retort B' from first eduction retort C by means of line 65, trap 5, and line 6 and thereby partially educt the rich shale therein. The liquid oil produced in second eduction retort B is removed by means of line I, trap 8 and line charge retort H. The discharge retort is isolated from. the rest of the system and the cooled -spent shale is discharged by means of line II to be disposed of as desired. After discharging spent shale the retort is then refilled with rich shale as shown by refill retort I by means of line 29 and the operation continued as aforemanner. Ai'ter second stage of eduction, valves are changed and shale submitted to the first stage of eduction, as shown by first eduction retort C. Hot lean shale gas and steam are introduced into first eduction retort C from second preheat retort F by means of lines I; and I wherein complete eduction takes place. The liquid oil produced in first eduction retort C is removed by means of line 4, trap I and line ii, to be handled in any desired manner. The relatively hot rich shale gas in first eduction retort C is introduced into second eduction retort B, as described above. After first stage of eduction in the first eduction retort C, valves are changed and the hot carbonaceous shale is submitted to the second stage of firing, as shown by second firing retort )3. Hot flue gas from the first firing retortE is introduced into second firing retort D by means of line i6 and thereby heating the carbonaceous shale to higher temperatures. The spent fiue gas in second firing retort D is then divided, part is withdrawn by means of line I, valve i1 and line ii to be disposed of as desired. The remainder of the spent fiue gas in second firing retort D is introduced into purging retort A by means of line I as described above. After the second stage of firing} valves are changed and the hot spent shale is submitted toflrst stage firing, as shown by first firing retort E. Fuel gas and air are introduced into first firing retort E by means of line l9 and burned therein so as to raise the shale to even higher temperatures. An excess air may be introduced to burn any residual carbonaceous material left in the spent shale. The fiue gas produced in firing retort E is introduced into retort D by meansof line i6 as described above. After first stage of firing, valves are changed and the very hot spent shale submitted to a second stage of preheating, as shown by second preheating retort F. The hot spent shale in second preheating retort F gives up heat to shale prior to discharge. .tion step is used a separate stage would be necesmentioned.

Figure 2 represents the complete process ineluding the necessary manifold to switch and transfer the individual retorts into the proper stages. Figure 2- carries the same numbers as shown on Figure 1 which describes the relationship oi the flow described in Figure 1 to the whole apparatus.

One modification of the present invention is to introduce water into discharge retort H Just prior to the discharging of hot spent shale. The introduced water on contacting the hot spent .shale would generate steamwhich could be used for operational purposes. This modification would also assist in iurther cooling the spent If this steam generasary, but the purging of the spent shale would be avoided.

Another modification of the present invention would be to increase the multiple stage operations shown in the drawings from the two-stage operation for each major step in the process, 1. e. firing, preheating and eduction, up to any desired number governed by expediency and operating conditions. A single stage operation may also be used, but the advantage of countercurrent fiow would be lost.

The process of the present invention may be widely varied. The invention may be adaptedto the second eduction stage. When retort A is hot lean shale gas and steam introduced therein from first preheat retort G by meansof lines 20 and II. If desired, additional steam may be added to second preheat retort F by means of line 22. The hot gases from second preheat retort F are introduced into first eduction retort C, and second eduction retort B, to act as an eduction medium, as shown above. Alter completing second stage of preheating, valves are changed and the somewhat cooled but still hot spent shale is introduced into first stage of preheating as shown by first preheat retort G. The cool lean shale gas from absorber H is introduced into first preheat retort G by means of .lines' It, 23, and 24 wherein said lean shale gas is heated by the sensible heat of hot spent shale therein prior to passing to second preheating retort F through lines 2| and II as described above. Steam is added to first preheat retort G as desired by means of line 15. In this operation the spent shale would be further cooled until it was ready for discharge. The excess of lean shale gas in first preheat retort G is removed through valve 2 and stack 21 to be handled in any desired manner; After first stage oi preheating, the valves are changed and thespent shale is submitted to discharging stage as shown by dissubjected to the second eduction stage, retort B is subjected to purging of air similar to first step or retort A. After a designated period of time retort A is changed to stage'three, i. e. first eduction period, simultaneously retort B changes to second eduction stage and retort C is subjected to air purging. This procedure is continued until all retorts are operating within one stage of the complete cycle. In order to transfer all retorts from one stage to another in a substantially simultaneous operation a master valve control probably should be used.

Shale should be crushed to pass a one-inch round sieve. Preferred size should pass a onehalf-inch round sieve and retained on a fivemesh sieve, although larger or smaller sizes may be used.-

The temperatures required for the proper eduction of shale in the first eduction retort may be between about 400 Rand 2000 F. depending on the type of shale employed and the products desired. Temperatures between about 400? F. and about 1000 F. are suitable ior most operaons.

The contact time required for reasonably complete eduction in both of the eduction stages may be as low as-0.01 second or less, and generally will not exceed about 24 hours, thelonger times oi contact within this range being required where The amount of steam and hot lean gas introduced into first and second eduction stages is controlled .to obtain the proper temperatures and thereby the right degree of eduction.

The foregoing description of my invention is I notto be taken as limiting my invention but.

only as illustrative thereof since many variations may be made by those skilled in the art without departing from the scope of the following claims.

I claim:

1. A multistage method for the recovery of shale oil from crushed oil shale which comprises treating the shale successively in the following stages: (1) purging, (2)- partial eduction, (3) complete eduction, (4) further heating, (5) burning, (6) first cooling and (7) second cooling, purging the shale in said purging stage with a purging medium consisting of hot flue gas produced in said further heating stage, partially educting shale oil and rich shale gas from said purged oil shale in said partial eduction stage by means of a secondary eduction medium consisting of hot rich shale gas and steam produced in rich shale gas, further separating said rich shale gas into hydrocarbons and residual learn shale gas, completely educting shale oil and rich shale gas from said partially educted oil shale in said complete eduction stage by means of a primary eduction medium consisting of hot lean shale gas and steam produced in said first cooling stage, withdrawing shale oil, rich shale gas and steam from said complete eduction stage, separating said-shale oil from said rich shale gas and steam, employing the resulting rich shale gas and steam in said partial eduction stage as the secondary eduction medium, heating said hot carbonaceous shale in said further heating stage by means of hot flue gas produced in said burning stage, withdrawing the resulting flue gas from said further heating stage, and employing it as the purging medium in said purging stage, burning the further heated carbonaceous shale by means of fuel tial eduction stage by means of a secondary eduction medium consisting of hot rich shale gas and steam produced in said complet'e eduction stage, ,withdrawing shale oil and rich shale gas from said partial eduction stage, separating said shale oil from said rich shale gas, further separating the rich shale gas into hydrocarbons and residual lean shale gas, completely educting shale oil and rich shale gas from the partially educted oil shale in said complete eduction stage by means of a primary eduction medium consisting of hot lean shale gas and steam produced in said first cooling stage, withdrawing said shale oil and rich shale gas and steam from said complete eduction stage, separating said shale oil from said rich shale gasand steam, employing said rich shale gas and steam in said partial eduction stage as the secgas and air in said burning zone to obtain hot with said hotspent shale first in said secondcooling stage and then in said first cooling stage.

2. A method for the recovery of shale oil from crushed oil shale which comprises employing a series of units wherein each unit within said series passes through a distinct and different stage of a complete cycle and changes simultaneously with the changes of each and every other unit, wherein each cycle comprises treating the shale successivelyin the following stages: (1) purging, (2) partial eduction, (3) complete eduction, (4) further heating, (5) burning, (6) first cooling and (7) second cooling, purging said oil shale in said purging stagewith a purging medium consisting of hot flue gas produced in said .further heating stage, partially educting shale oil and rich shale gas from the purged oil shale in said parondary eduction medium, heating said hot carbonaceous shale in said further heating stage by means of hot flue gas produced in said burning stage, employing the resulting flue gas from said further heating stage as the purging medium 'in said purging stage, burning the heated carbonaceous shale by means of fuel gas and air in said burning zone to obtain hot spent shale and hot flue gas, withdrawing said hot flue gas from said burning zone and employing it in said further heating. stage, and'heating said primary eduction medium consisting of lean shale gas and steam by direct heat exchange with said hot spent shale first in said second cooling stage and then in said first cooling stage.

3. A process according to claim'2 in which the eduction medium in each eduction stage is passed PHILIP H. JONES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,011 Pelzer June 16,1938 860,058 Von Post July 16, 1907 889,150 Von Post May 26, 1908. 1,191,870 Bussey July 18, 1916:.

1,317,514 McCaskell Sept. 30, 1919 1,503,093 Catlin July 29, 1924 1,604,738 Dommick 0ct.,26, 1926 1,631,637 Longlney June 7, 1927 1,675,315 Trent June 26, 1928 1,704,956 Trumble Mar. 12, 1929 1,713,794 Trumble May 21, 1929' 1,836,051 Trumble Dec. 15, 1931 2,435,746 Jones Feb. 10, 1948 FOREIGN PATENTS Number Country Date 336 Great Britain Jan. 25, 1878 487,983

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